The Great Barrier Reef Marine Park Authority (GBRMPA), which carried out the first survey for 2017 over the area between Carins and Townsville in Queensland state, declared widespread damage from an underwater heatwave.

It is believed that the cause of bleaching of large areas of coral is warmer water temperatures. Warm waters force corals to expel algae living within their tissues, turning themselves white. The coral may die on the six to 12 months after bleaching.

It was estimated that two-thirds of coral coverage died in a 700 km stretch of the reef north of Port Douglas last year due to bleaching.